Self aligning take-up links



April 30, 1957 F. PARRY SELF ALIGNING TAKE-UP LINKS Filed Dec. 9, 1955 INVENTOR Frank Parry lgmwu A TORNEY WITNESS SELF ALIGNING TAKE-UP LINKS Frank Parry, Trumbull, Conn, assignor to The Singer Nlanufacturing Company, Elizabeth, N. 3., a corporation of New Jersey Application December 9, 1955, Serial No. 552,174

4 Claims. (Cl. 112-241) This invention relates to thread take-up mechanisms for sewing machines, and more particularly to a needle thread take-up mechanism employing a crank-operated oscillatory thread take-up lever.

It is an object of this invention to provide in a sewing machine thread take-up a means automatically compensating for any misalignment which may occur between the axis of the actuating crank and that of the means by which the take-up lever is pivoted for oscillation.

It is also an object of this invention to provide an alignment compensating device for a thread take-up lever which has little or no effect upon the path .of travel of the thread engaging extremity of the take-up arm.

With the above and other objects and advantages in view as will hereinafter appear, this invention comprises the devices, combinations, and arrangements of parts hereinafter described and illustrated in the accompanying drawings of a preferred embodiment in which:

Fig. 1 is a front end elevational view of the-bracketarm head portion of a sewing machine frame having the take-up mechanism of this invention applied thereto.

Fig. 2 represents a side elevational view of the mechanism of Fig. l with the bracket-arm headportion of the machine frame being illustrated in vertical cross section.

b Fig. 3 represents an enlarged cross sectional view taken substantially along line 33 of Fig. 1.

Fig. 4 represents an enlarged cross sectional view taken substantially along line 4-4 of Fig. 2, and

Fig. 5 representsa cross sectional view taken substantially along line 5-.5 of Fig. 3.

Referring to the drawings, Figs. land 2 illustrate the thread take-up mechanism of this invention as. embodied in a bracket-arm head portion 11 of a conventional sewing machine. The bracket-arm head 11 is formed with a cavity 12 adapted to be closed as by a-face plate 13 secured to the frame, as shown in Fig. 2, by aknurled 2,790,406 Patented Apr. 30, 1957 is derived from the counterbalanced crank 24 as will be described below. i

The take-up lever, as best illustrated in Figs. 1 and Zcomprises a hub 32 from one extremity of which extends 5 an arched take-up arm 33 formed at its free extremity ing from thehub 32 of the-take up lever is an actuating 15 link lever arm 35, preferably in the form of acylindrical rod, which is embraced by .a slide block 36 carried by a take-up actuating crank-pin .37 which is rotatably journaled in a boss 38 formed on theneedlebar driving 26. The actuating lever arm 35 extends symmetrically about the above mentioned reference plane containing the take-up arm and, in addition, the actuating lever arm extends substantially at right angles to a line X X in Figs. 1, 4 and 5 which line is arranged in the reference plane and joins the thread take-up eyelet 34 with the axis of the fulcrum pin 31.

In manufacture ofthe sewing machine, perfect parallelism of the take-up lever fulcrum pin 31 with the main shaft 23 is inherently extremely difiicult to obtain. The crankpin 25 is similarly subject to slight deviation out of parallelism with the main shaft 23, and likewise, the take-up actuating pin 37 with respect to the crank pin 25. Although the tolerances vorpermissible deviations .in these parts may be made quite small, the tolerances are cumulative and together can result in an appreciable misalignment of the slide block 36 with respect to the cylindrical actuating arm 35 of the take-up lever. It is anobject of thisinvention to provide a means com- 5 pensating for such-misalignment thereby obviating the possibility of binding between the parts or harsh actions therebetween with high friction forces.

To this end, the take-up lever 30 is journaled on the fulcrum pin-3l by means of a novel bearing and hub arrangement which enables the take-up lever to oscillate about any of a range of axes varying out of parallelism with. the axis of the-fulcrum pin to an extentjsuflicient to compensatefor any misali nment occasioned by an unfavorable accumulation of tolerances in the disposition 5 ,of the main shaft- 23, crank pin 25 and take-upactuat ing crank pin 37 with respect to the fulcrum pin 32. V

The hubof the take-up lever of this invention, as best illustrated in Figs. 3, 4and-5, is formed with aclearance bore. 4t) of substantially larger diameter than that of the fulcrum pin 33. Seated within one extremity of t-he thumb screw 14. Extending into the head cavity is a foot 26 which opposes a conventional feed dog 21 carried beneath a work supporting throat-plate 22.

Reciprocatory motion is imparted to the needle-bar 15 from a main shaft 23 to which is fixed a counten balanced crank 24 extending into the head cavity. A needle-bar actuating crank pin 25 fixed inthe crank 24 is embraced'by a needle-bar driving link 26 which is connected, in turn, to a pivot pin 27 extending laterally from the needle bar. v

In the sewing machine illustrated in the drawings, control ofthe needle thread is attained by means of a takeup lever, indicated generally as 3%, which is carried for oscillatory motion on a fulcrum pin 31 fast in the bracket-arm head. Oscillatory motion of the take-up lever 'bore ti is a conventional needle bearing '1 comprising an outer race member 42 formedv to confine a single row of needle bearing elements 43 which bear directly upon the fulcrum pin 33. The needie bearing 41 isdis- 5 vposed substantially symmetrical about the vertical reference plane ofthe take-up lever and, therefore, is also symmetrical about theline X X as illustrated in Fig. 4. The'needle bearing is narrow in width having an effective bearing width preferably less than 'half its in- 50 side diameter. By effective bearing width is meant the length of the line of contact between any bearing needle with either the fulcrum pin or the outer bearing race.

The normal running fit between the bearing 41 and the fulcrum pin31 provides suhicient clearance therebe 5"tween so that when a narrow bearing is ntilizedfas set forth above, a universal connection is provided between the take-up levers. and the fulcrum pin. Tie limits of universal movement of the lever are inversely proportional to the effective width of the bearing, however, it

has been found that when the effective width of the bearing is half of the inside diameter of the bearing,

sufficientuniversal movement is provided to accommodate any misalignment which may occur when conventional tolerances are maintained between the parts.

At the extremity of the take-up lever hub opposite that at which the bearing 41 is disposed, the hub is formed engaging eye. The walls 4545 thus confine the universal movements of the take-up lever made possible by the narrow bearing, to turning movements about the line X X as an axis. The advantage of so confining or limiting the universal movementof thetake-up le- -ver is that since the line XX passes through the thread eyelet 34 of the take-up lever, the universal movements of the lever will have no eifect upon the path of motion of the thread eyelet. Since the eyelet path of motion is of critical importance and any deviation would be reflected in the consistency of the stitches being produced, this functioning of the Walls 45-45 is highly important. The restriction of the universal movement of the takeup lever, moreover does not reduce the effectiveness of this construction in its capacity to accommodate misalignment of the pins 31, 37, 25 and shaft 23 since the turning motion of the take-up lever about the line XX is the only component of universal movement which is effective to counteract for nonparallelism of the pins and shaft.

This invention thus provides an inexpensive take-up mechanism which is fioatingly mounted to prevent binding or abnormal wear because of misalignment of the driving and supporting parts, but which is arranged such that the path of motion of the thread-engaging eyelet will not be affected by movements made to accommodate the misalignment of the parts.

Having thus described the nature of the invention, what I claim herein is:

l. A thread take-up lever for a sewing machine adapted to be journaled for oscillation on a fulcrum pin carried in the sewing machine and comprising, a hub, 21 take-up arm extending from said hub and formed at its free extremity with a thread-engaging eye, said hub being formed with a bore, means constricting each extremity of said bore, said means comprising at one exremity an annular bearing member carried in said bore and having an effective bearing width less than half its inside diameter, and at the opposite extremity means providing a pair of opposed substantially parallel walls one at each side of said hub bore defining a slot'disposed substantially perpendicular to a line joining the axis of said hub bore with said thread-engaging eye,

2. A thread take-up lever for a sewing machine adapted to be journaled for oscillation on a fulcrum pin carried in the sewing machine and comprising, a hub formed with a bore, 'a take-up arm extending from said hub and formed at its free extremity with a thread-engaging eye disposed to'intersect a reference plane perpendicular to said hub bore, first and second means constricting said bore at spaced points therein, said first means comprising an annular bearing member carried in said bore and disposed substantially symmetrical about said reference plane and said bearing member having an effective bearing width of less than half its inside diameter, and said second means comprising a pair of diametrically opposed flanges extending radially into said hub bore presenting opposed parallel walls disposed one at each side of said hub bore and substantially perpendicular to a line in said reference plane joining said thread eye with the axis of said hub.

3. A take-up lever for a sewing machine having a frame, actuating mechanism in said frame including a take-up actuating crank-pin and a fulcrum pin carried in said frame and adapted to support said take-up lever, said take-up lever comprising a hub formed with a clearance bore adapted loosely to accommodate said fulcrum pin, a take-up lever arm extending from one extremity of said hub, said take-up lever being formed with a thread-engaging eye, an actuating lever arm extending from said extremity'of the hub substantially at a right angle to the line joining the axis of said hub bore with said thread-engaging eye, slidingly pivoted driving connections between said take-up actuating crank-pin and said actuating lever arm, and a universal connection between said take-up lever and said fulcrum pin comprising an annular fulcrum pin embracing bearing member carried in the clearance bore of the hub at the juncture of the take-up and actuating lever arms thereon, and hub bore constricting elements disposed at the opposite extremity of said hub, said constricting elements being disposed to protrude inwardly toward the axis of said hub clearance bore from diametrically opposite sides thereof defining a fulcrum pin embracing slot extending substantially parallel to said actuating lever arm.

4. A thread take-up lever for a sewing machine adapted to be journaled for oscillation on a fulcrum pin carried in the sewing machine and comprising, a hub, a takeup arm extending from said hub and formed at its free extremity with a thread-engaging eye, said hub being formed with a bore, means constricting each extremity of said bore, said means comprising at one extremity an anti-friction bearing member including an outer race member carried in said bore, a plurality of anti-friction bearing elements confined in said outer race, said antifriction bearing elements having an effective bearing width less than half of the inside diameter of said antifriction bearing member, and at the opposite extremity of saidjbore a pair of opposed inturned flanges presentin opposed substantially parallel walls one at each side of said hub bore defining a slot disposed substantially perpendicular to a line joining the axis of said hub bore with said thread-engaging eye.

References Cited in the file of this patent Uurrnn STATES PATENTS 2,063,280 Waterman Dec.8,1936 

